Modification work on in-service A380s is in full swing, but will only be completed by the end of 2015
Emirates' follow-up order for 50 more has been a great relief for the sales department. And the engineering group continue to point out that the manufacturer's largest jet is now “a normal serial program,” as executive vice president for programs, Tom Williams, puts it. But this is not yet the case for its customers.
While Airbus has identified and developed short- and long-term fixes, as well as a new wing design for the aircraft, airlines are still feeling the effects of the modification work required to repair the cracks in wing rib feet, which were discovered during routine maintenance. Some of the operators will feel the pain until the end of 2015, as the needed work can take each afflicted aircraft out of service for up to eight weeks.
Airbus has completed the needed modifications on fewer than one-quarter of the in-service A380 fleet. According to Williams, 27 aircraft have received the permanent fix. Work on an additional 22 aircraft is underway, but this is for operators who have opted for the step-by-step approach proposed by Airbus. Aircraft can either be taken out of service for up to eight weeks to complete a one-process modification, or work can be done in stages, allowing the airlines to use their aircraft on commercial runs in between shop visits. Williams expects that 11 more aircraft will have been fully modified by the end of June.
Several causes contributed to the wing-component problem. One was the use of a specific aluminum alloy (7449) and its heat treatment. Though the alloy saved weight, it rendered the component more brittle, leading to cracking. Another was attributed to the process of attaching the wing skin to the ribs; excessive loads were placed on components during assembly.
The problem was compounded by a failure to properly account for the temperature-induced material expansion and contraction during operations.
As part of the retrofit, Airbus is replacing ribs using the more conventional Al 7010, which is well-proven in aerospace applications. The retrofit goes beyond the areas where cracks have been found to include ribs 48 and 49 at the outer end of the wing. The retrofit includes replacing all 23 hybrid ribs (composed of a mix of 7449 aluminum and composite) with all-metallic ribs made with 7010 alloy. The rib feet also have been redesigned to strengthen them, and an inspection manhole in the area where the cracking occurs has been reinforced.
The permanent retrofit was approved by the, so the affected aircraft is certified to be returned to the full expected service life of 19,000 cycles.
A set of checks and, if needed, interim repairs, is currently required after as few as 500 cycles for aircraft that are awaiting the retrofit. That alone is causing serious operational disruptions for the affected airlines.
Emirates, by far the largest operator of the A380 with a fleet of 44 of the type, says work on 35 of its aircraft that had been delivered with wings of the old design will be completed by the end of the year. Four maintenance, repair and overhaul providers have been tapped by Airbus to make the changes. A further nine aircraft have been handed over to Emirates; these had the replacement completed prior to delivery.
Airbus has informed its operators that the wing rib feet replacement is a “warranty issue” and therefore covered by the manufacturer. There have been disagreements (and some behind-the-scenes settlements) about Airbus's responsibility to compensate airlines for loss of revenue. Emirates said in 2012 that the A380 repair issues dealt a $30 million monthly toll to its bottom line.
All 25 A380s delivered last year initially received the wings that were prone to cracking in some areas, but have since had the permanent fix performed either in Broughton, England, (where the wings are built) or at the final assembly line in Toulouse before being delivered to airlines.will be the first carrier to receive its A380s with newly designed wings, later this spring.